# research

## velocity potential for a rate formulation

Choose a channel featured in the header of iMechanica:
Free Tags:

I have a question making me no sleep. In the elastic theory we have a separable Lagrangian L = T(v) + W(u) since we can write the internal elastic energy as a function of displacements. What happens if we use a rate form for the strain and the stress? Can we write the potential energy in terms of just velocities? If that is the case the stationary path of the Lagrangian reduces to:

d/dt (dT/dv - dW/dv)  = 0

## Fracture energy for crack propagation in a 4 points bending notched beam

Hi everyone,

Anyone can tell me how to determine the fracture energy for crack propagation in a 4 points bending notched beam (mode I)?

## Derivatives of a volume integral with singular kernel

Hi everybody,

In fact, I encounter this problem in my research and I would be grateful if someone can help. In micro mechanics, there are many problems concerning Green functions, e.g: the displacement is calculated from the distributed force in the domain, etc. Consider the following integral to determine the displacement field.

## Manchester biophysics meeting --- DNA nanomachines

The 2-day conference of biophysics in Manchester had just finished recently. It is really a meeting with a tight schedule and lots of new stuffs.

The meeting took place in the new building of multi-decipline biocenter in Manchester University. One interesting speech was given by Prof. Andrew J. Turberfield

from Oxford university. Recently his group focuses on build some small molecule machines using DNA as the building block. It is just like

## How to represent the fiber-reinforced hyperelastic part

Choose a channel featured in the header of iMechanica:

Hey guys,

I am right now doing a FEA on cervical spine, however, the annulus property is complex, and I need to represent it by a fiber-reinforced hyperelastic part, I tried a lot, but still are nowhere.

Can anybody tell me how to assign some embeded layers with elastic rebar element to a solid part ?

Thanks a lot.

## Embeded element

Does anybody know how to represent a fiber-reinforced annulus part: ground substance is hyperelastic with neo-hooke coefficient; fiber-reinforcement are elastic?

## COMSOL, PDE

Hi

Has any body used comsol pde. please guide me through the basics of comsol methods.

Cheers

## Numerical integration of non-polynomial functions

Hello colleagues,

Would anybody know good references on numerical integration of non-polynomial functions? It would be enough for me to obtain one-dimensional rules. Of course, it could have impact for XFEM applications, but for another, improved XFEM method that we are developing.

Note  that I am not talking about integrating singularities, but non-polynomial functions. Examples:

sqrt(x)

cos(x)

sin(x)

product of these.

Thanks for any help,

Stephane

## Any open source code to generate carbon nanotube cap?

Generation of open ends carbon nanotubes coordinates (atomic positions) is easy and the generation of cap for these carbon nanotubes is extremely difficult. Some of the half-fullerenes (C60, C240, C540…) fit as a cap for the armchair and zigzag nanotubes. NanotubeModeler  (http://www.jcrystal.com/products/wincnt/index.htm) software generates the carbon nanotubes with cap but they are limited to few armchair and zigzag configurations.

## Co-evolution of local thinning and debonding

A 1um-thick Cu film was deposited on Kapton 50HN substrate, with a thin Cr interlayer to improve adhesion. The specimen was in-situ annealed at 200oC for 30min after deposition.

This FIB image was taken after the specimen was uniaxially stretched to 50% and released.

## PhD in Applied Mechanics

Hi, guys...

I am a Mechanical Engineer (newly graduated).

Can somebody tell me where I can find a very good PhD studentship in APPLIED MECHANICS (i.e. vibro-acoustics, control systems, vehicle dynamics, etc...) in Europe?

I'm getting crazy with that... I hope somebody can help me.

NV

## Material Instability - Questions

Hello All:

I'm interested in learning more about material instability, for example the localization criterions of Hill (1962) and Rudnicki and Rice (1975).  I also am aware of work by Rice (1976), in which a perturbation is made to the displacement field in the form of a plane harmonic wave, resulting in a strong ellipticity instability condition that looks like Det(Q), where Q = c_ijkl + Sigma_jk, i.e. a competition between material softening and stress increase determines the instability.  Furthermore, this stability criterion is developed assuming an infinite body.

## HIEM to 3D Crack in FC-EMTE-MCs

Hypersingular Integral Equation Method to 3D Crack in Fully Coupled Electromagnetothermoelastic Multiphase Composites